Disperse dyeing of polyester cellulose blends with an aqueous suspension of the sulfonated polystyrene sodium salt



United States Patent Ser. No. 718,001

Int. Cl. D06p 3/82 s. (:1. 8-21 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to an improved dyebath composition comprising water, a colorant and a water-soluble sodium salt of a sulfonated polyalkenylraromatic monomer, and more particularly to such a composition which retards and minimizes dye migration during dyeing.

This application is a continuation-in-part of U8. Ser.

No. 617,838 filed Feb. 23, 1967, vnow abandoned.

The coloring of synthetic, man-made fibers and filaments, such as those prepared from polyesters and polyamides, is frequently beset by troublesome problems. Those problems have not been eased by the increased blending of fiber species, by the different weaves and knits when dyeing piece goods, by the use of finishing agents, and by other procedures involved in the textile trade.'Concurrently, the demands have increased for improved fastness to washing, drycleaning, sunlight and other environmental conditions.

Dye migration is an especially troublesome proble with those dyeing processes where the dyestuff is applied to fabric by padding, then the fabric dried, followed by dye fixation by heat or steam. In all conventionaldying methods (tenter frame, dryingcans),.heat is applied to the surface of the fabric. The vaporated water-is swept away by a stream of air. Thus, the surface of the fabric dries first. Then more water from the interior of the fabric migrates to the surface and is evaporated, and so on until the fabric is dry. In this migration to the surface, the water carries along some of the dye. Consequently, the surface of the fabric is dyed to a deeper shade than the interior of the fabric. Furthermore, if.;the-drying rates of the two surfaces of the fabric are different, i.e., heat is applied unevenly to the two surfaces or from selvage'td selvage, difference in depth of shade of the face and back or side to side results.

To reduce dye migration, especially in hot flue drying machines, a small amount of thickening agent is sometimes added to the padding liquor. Generally, polyelectrolytes, such as sodium alginate, sodium carboxy methyl cellulose, sodium polyacrylate, are recommended as thickeners. The action of these thickeners is as follows:

When the fabric begins to dry, water is driven off and the concentration of the thickener of the fabric in the remaining water gradually increases. Thus, the liquor on the fabric becomes more viscous. The more viscous the liquor, the more resistant it is to dye migration.

However, when heat is applied to the wet fabric, the liquor on the fabric is heated up. It is a known fact that the viscosity of solutions of electrolytes generally decreases with increasing temperature. Therefore, the effect of prevention of dye migration starts to appear only after some of the water is evaporated from the liquor on the fabric but not during the initial heating period.

The present invention is designed to minimize or to prevent that dye migration. That objective is achieved by using an aqueous dyebath containing the dyestufi and certain amounts of an alkali metal salt of a sulfonated polyalkenyl aromatic polymer.

The water-soluble, linear, high molecular weight polymer sulfonates with which this invention is concerned correspond to addition polymers of monoalkenyl aromatic sulfonates having the general formula:

wherein Ar is a divalent aromatic radical, R is hydrogen or methyl, and M is a cation. Specific examples of sulfonates which are used in accordance with this invention are water-soluble, linear, high molecular weight polymers of styrene sulfonic acids, a-methyl-styrene sulfonic acids, ar-methylstyrenesulfonic acids, and the watersolublesalts of such resin sulfonic acids.

Thelermffsulfonate is used herein to mean the salts of the above-polymers with M in the foregoing formula being a cation, including metal, ammonium, amine and like salt-formingjcations. Specific examples, for purposes of illustration, of suitable salts are the sodium, potassium, calcium, ammonium, and. amine salts of the polymer sulfonates.

The addition 'polymerscorrespond to homopolymers of the monoalkenyl aromatic sulfonates, copolymers of two or more such sulfonates, and copolymers of one or w more of such sulfonates and one or more of other monoethylenically unsaturated'monomers wherein the monoalkenyl aromatic sulfonate is at least 60 percent by weight of the total polymer. In the latter such polymers, units corresponding to a monoalkenyl aromatic sulfonate are additionally combined with units corresponding to one or more kinds of monoethylenically unsaturated compounds, examples of which, for purpose of illustration, are styrene, a-methylstyrene, isobutylene, ethylenically unsaturated esters, e.g., 1-12 carbon atom alkyl esters of acrylic or methacrylic acids, vinyl esters of fatty acids, such as vinyl acetate, vinyl chloride, vinylidene chloride,

r methyl isopropenyl ketone, methyl vinyl ether, and acrylonitrile.

The term water soluble is used herein to mean that the polymer. sulfonates form true or colloidal solutions in pure water, which solutions are practically free of gel.

particles and are infinitely dilutable with water.

By high molecular weight is meant that the polymer sulfonates should have a molecular weight of at least about 500,000. For, practical reasons, such as ease of'dissolution, it is preferred that the molecular weight not exceed about 10,000,000.

The water-soluble, linear, high molecular weight polymer sulfonates for use in this invention are obtained either by polymerization of the corresponding monoethylenically unsaturated monomers or by sulfonation of --a starting polymer of monoethylenically unsaturated monomers. In many instances, the desired polymer sulfonatewill be available commercially. If any other is desired, methods for its preparation will be available in the literature as for example inU.S. 3,206,445 issued Sept. 14, 1965 to Volk. It is the polymer sulfonate that is controlling in the present invention andnot the procedure by which it is prepared. e

In accordance with this invention, the viscosity of aqueous dyebath solutions is advantageously increased by incorporating therein small amounts of water-soluble, linear, high molecular weight polymer sulfonate of the kind described above. The concentration of the polymer sulfonate to be used in the aqueous dyebath composition will depend on the kind and molecular weight of the polymer sulfonate and the viscosity desired in the dyebath. In most instances, the amount of polymer sulfonate will be less than one weight percent of the water and sulfonate solution and frequently will be 0.01 or 0.02 weight percent. Although more than 0.1 weight percent of the polymer ,sulfonates of this invention may be used, there is little additional benefit that accrues therefrom. In contrast, the prior used polyelectrolytes, such as sodium alginate, required the use of at least 0.2 weight percent to achieve level dyeings.

The dyebath composition of the present invention finds utility in all dyeing techniques utilizing an aqueous dyebath. It is especially advantageous in those procedures using a thickened solution or paste. Typical of those advantageous dyeing processes are those wherein the dyestufi is padded or printed onto the goods followed by drying and fixation by heat or steaming. The ThermosoF technique described in the American Dyestuff Reporter 42, pages 1-2 (1953) is one such process wherein the dyestuif is formed into a paste dispersion which is then subjected to both elevated temperature and relatively high pressure and the paste subsequently removed.

The process is useful with any dyestuff that is utilizable in such processes and techniques as aforementioned. Exemplary of those dyestuffs are Eastman polyester red B C.I. Disperse Red 88); Latyl yellow 4 RL (C.I. Disperse .Yellow 23 CI. 26070); Eastone red R (0.1. Disperse Red 17 CI. 11210); Interchen blue B (Cl. Disperse Blue 3 CI. 61505); and Latyl brown M3 (C.I. Disperse Brown 2).

The polymer sulfonates of this invention may be used in conjunction with the conventional dyebath additives, such as dye assistants, protective screeners and the like.

The present inventive concept is illustrated by the following examples wherein all parts and percentages are by weight.

EXAMPLE 1 An aqueous pad bath composition was prepared by dissolving in water 1 percent Eastman polyester red B (Color Index Disperse Red 88) 0.2 gram per liter of the sodium salt of sulfonated polystyrene having a molecular weight of 8 million prepared by the dehydrohalogenation and subsequent polymerization of beta-bromoethyl phenyl sulfonate as per U.'S. 3-,206,445,-and'0.3 gram per liter of Du Pont Compound No,-8S. The liquor was padded on a 65/35 polyethylene tere'phthalate/ cotton fabric, dried at 250 F. until dry, and heat fixed at 410 F. for two minutes.

The procedure was repeated using 2.0 grams/liter of sodium alginate in place of the sulfonate.

When the quality of the dyeings was compared, they were the same.

EXAMPLE 2 The aqueous pad bath composition, as in Example 1, was prepared except that the sulfonate had a molecular weight of 2 million instead of 8 million. When the dyeing procedure of that example was repeated, the same quality dyeing was exhibited.

What is claimed is:

1. In a process for dyeing polyester/cotton blends of fibers, the improvement which consists in using an aqueous dyebath composition comprising water, a dispersed dye, and from 0.01 to 10.0 weight percent of a water-soluble sodium salt of a sulfonated polystyrene having a molecular weight of from about 2,000,000 to 8,000,000.

References Cited UNITED STATES PATENTS 2,955,009 10/1960 Pitts 8173 FOREIGN PATENTS 367,416 11/1930 Great Britain. 1,061,584 8/1952 France.

OTHER REFERENCES Schober, American Dyestutf Reporter, May 25, 1964, pages 418-420.

Tullio, American Dyestuff Reporter, May 23, 1966, pages 412419.

Boundry-Boyer, Styrene, Its Polymer and Copolymers and Derivatives, pub. by Rheinhold Pub. Co., New York City.

DONALD LEVY, Primary Examiner US. Cl. X.R. 

